Knowledge Bank

Phase-shift cavity ring down absorption spectrocscopy with a continuous laser was used to mesure the absorption coefficients and integrated cross sections for the fifth overtone of the C-H stretching vibration of ethylene, ethane, propane, n-butane, and n-pentane. The absorption spectrum is obtained by measuring the magnitude of the phase shift that an intensity modulated continuous laser beam experiences upon passing through an optical cavity. The detection sensitivity compares favorably with that of the pulsed laser `standard' cavity ring down technique.